Methods and apparatus for production of composite-coated rigid flat-rolled sheet metal substrate

ABSTRACT

Methods and apparatus for producing composite-coated rigid flat-rolled sheet metal substrate in which thermoplastic polymeric materials are selected and combined for dual-layer molten-film extrusion presenting a first-contacting tie-layer and an externally-located finish-layer which are simultaneously extruded for a single substrate surface at-a-time; in which tie-layer selection includes an ethylene-glycol modified PET, requiring a substrate-surface temperature between 230° F. and 300° F., and a maleic-anhydride modified polyethylene free of any substrate-surface heating requirement; the tie-layer provides sufficient green-strength-adhesion for a finish-layer selected from PBT, PET, and a combination of PBT and PET; each substrate-surface is separately activated for desired adhesion and separately polymeric coated; dual-surface finishing-processing is carried-out by remelting the coated polymeric materials for completing bonding of the dual polymeric layers on each inorganic-metallic protectively-coated surface of the substrate.

RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. ProvisionalApplication Ser. No. 60/468,705 filed May 7, 2003; and, is acontinuation-in-part of co-owned and co-pending U.S. patent applicationSer. No. 10/156,471 entitled “METHODS AND APPARATUS FOR SURFACEPREPARATION AND DUAL POLYMERIC LAYER COATING OF CONTINUOUS-STRIPFLAT-ROLLED SHEET METAL, AND COATED PRODUCT” filed May 28, 2002 and ofco-owned and co-pending U.S. patent application Ser. No. 10/191,411entitled “PROCESSING AND APPARATUS FOR PRODUCTION OF ENGINEEREDCOMPOSITE COMBINING CONTINUOUS-STRIP SHEET METAL AND THERMOPLASTICPOLYMERS”, filed Jul. 9, 2002 as a continuation-in-part of co-owned U.S.patent application Ser. No. 10/156,473 (now abandoned), filed May 28,2002, entitled “PROCESSING AND APPARATUS FOR PRODUCTION OF ENGINEEREDCOMPOSITE COMBINING CONTINUOUS-STRIP SHEET METAL AND THERMOPLASTICPOLYMERS”, as a continuation-in-part of co-owned (now abandoned) U.S.patent application Ser. No. 09/767,785, entitled “POLYMERIC COATED METALSTRIP AND METHOD FOR PROCESSING SAME”, filed Jan. 23, 2001 as acontinuation-in-part of co-owned (now abandoned) U.S. patent applicationSer. No. 09/490,305 entitled, “POLYMERIC COATED METAL AND METHOD FORPRODUCING SAME”, filed Jan. 24, 2000.

INTRODUCTION

[0002] This invention relates to coating flat-rolled sheet metal,polymeric coating methods, polymeric coating apparatus, andcomposite-coated work product. In its more specific aspects, thisinvention is concerned with selecting rigid flat-rolled sheet metalsubstrate presenting an inorganic-metallic protective coating for eachplanar surface of the substrate; and, with molten thin-film extrusion ofdual-layer thermoplastic polymeric materials for augmented combinationof metallurgical and polymeric properties in the production of anengineered composite-coated flat-rolled sheet metal work product.

OBJECTS OF THE INVENTION

[0003] Important objects involve selecting: flat-rolled sheet metalsubstrate, an inorganic-metallic protective coating for each surfacewhich is capable of being activated for in-line adhesion, and ofdual-layer polymeric coating materials so as to increase performance anddurability of work product for fabricating opportunities.

[0004] A related object involves pre-selecting polymeric materials forenhanced adhesion of a molten-thin film tie-layer, which first contactsa selected inorganic metallic-protective surface and, also, forinterlinking with a selected molten polymeric materials, co-extruded asa finish-layer.

[0005] A further specific object involves selecting thermoplasticpolymeric materials capable of molten thin-film extrusion, selecting aninorganic metallic protective surface for flat-rolled sheet metal; and,with co-extruded exterior-finish thermoplastic polymeric materialsselected for surface properties complementing those of a selected sheetmetal.

[0006] A further related object is achieving desired surface coverage ofpolymeric coating materials by utilizing continuous line coatingoperations correlating substrate presentation with first-contactingtie-layer polymeric materials selections; and, achieving uniformthickness gauged dual-layer polymeric material.

[0007] The above and other objects and contributions of the inventionwill be disclosed in more detail in describing embodiments of theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Pre-selected rigid flat-rolled sheet metal continuous-stripsubstrate with inorganic corrosion-protected opposed planar surfaces issupplied at station 10 of FIG. 1. Sheet surface thickness gauge ispre-selected to be greater than foil gauge for the selected sheet metalfor directing rigid sheet in-line at station 11 for travel in thedirection of its length. The flat-rolled sheet metal is selected tocontribute desired mechanical properties, such as tensile strength,impact hardness, and ductility for composite coated work product, forfabrication into finished market-usage products, such as housings forappliances, panels for transportation equipment, building construction,and the like. Pre-selecting of polymeric finish-surface polymericmaterials concentrates on contributing to formability,abrasion-resistance and impact-hardness properties for optimumperformance and durability of the composite-coated sheet metal.

[0009] Present concepts involve selecting formulated thermoplasticpolymeric materials which are compatible and capable of combining formolten film co-extrusion; and, which can be relied on for bonding aninner-located polymeric material with an activated metallic-surface andinterlinking with externally-located finish-layer polymeric materials.Further concepts involve in-line operations which enable carrying-out aplurality of distinct operations, in sequence, separately on eachopposed metallic surface, prior to combined finishing processing of bothsurfaces in-line.

[0010] An inorganic-metallic surface coating is selected so as toprotect each of the pair of substantially-planar opposed substratesurfaces, extending widthwise between lateral edges, for coatingenhancing of dual-layer polymeric materials.

[0011] In-line surface activation for polymeric coating of solely asingle metallic surface is carried out at station 12. Thatsingle-surface activation involves open-flame impingement whichburns-off light surface oil and associated debris, if any, whileinitiating surface-activation by controlling chemical content of theimpinging flame producing an oxidizing reaction for enhancing polymericadhesion. Corona-discharge ionization of the gas, contiguous to thatsingle metallic surface, contributes to sustaining surface-activationfor enhanced polymeric adhesion. Open-flame treatment, corona-dischargetreatment, and/or their combination can be selected for activating asurface to enable a chemical bonding of related organic polymericmaterial with an inorganic activated metallic surface.Surface-activation methods and apparatus are described in more detail inrelation to subsequent figures.

[0012] Thermoplastic polymeric materials, pre-selected at station 14 ofFIG. 1, are formulated for co-extruding dual-layers, for performingdual-functions, as associated with said single activated-surface. Duringdeposition, the first-contacting layer of the co-extruded-film comprisesa “tie” layer. Formulations for thermoplastic polymeric materials havebeen found for carrying out desired surface coverage; which include:in-line processing capable of presenting an activated-surface, at atemperature which is correlated with the selected tie-layer polymericmaterials for desired surface coverage purposes of theactivated-surface. For example, ethylene-glycol modified polyethyleneterephthalate (PET) comprises a tie-layer selected for desired in-linetravel properties surface coverage and polymeric linking functions,which utilizes a correlated- temperature for the activated-surface ofabout 230° F. to about 300° F. Another contribution of the inventioninvolved finding a polymeric material formulation for the tie-layer,capable of fulfilling those desired purposes, while providing fordesired surface coverage when presenting an activated-metallic-surfaceat ambient temperature. For example, maleic anhydride modifiedpolyethylene has been found which fulfills desired tie-layer functions;and, enables desired coverage of an activated-surface free of anysurface heating requirement.

[0013] Providing desired “tie-layer” characteristic, while eliminatingany requirement for pre-heating an activated-surface, has advantagesduring in-line operations. Being free of heating requirements for theactivated-surface helps to decrease heat-removal requirements fro thesheet metal substrate, during in-line travel, for solidifying the moltenextruded polymeric materials; also, minimizes handling problems duringin-line operations, and facilitates multiple polymeric selections, whenactivating and presenting a single corrosion-protected substrate surfaceat-a-time for polymeric coating operations.

[0014] An important contribution of the tie-layer is providing fordesired in-line travel between organic polymeric materials and aninorganic metallic surface of the flat-rolled sheet metal substrate. Afurther function for the tie-layer is polymeric interlinking with moltenco-extruded polymeric material selected for exterior-finish propertieswhich complement properties of other components of the composite-coatedflat-rolled sheet metal work product.

[0015] In a specific embodiment, the polymeric exterior-finish polymericmaterial is selected from the group consisting of (i) a combination ofpolybutylene terephthalate (PET) and polyethylene terephthalate (PET,(ii) PBT, and (iii) PET. Polymeric materials for the externally-locatedfinish-layer are selected for such properties as surface toughness,abrasion-resistance, or other properties helpful market-usage industrialfabrication, and use, of the composite-coated work product; that is,added surface finishing, after fabrication, can be substantiallyeliminated; which is part of the objective to properly combining sheetmetal properties and properties of selected composite coatingcombinations which contribute to increasing performance and durabilityof composite-coated market-usage work product.

[0016] At station 15 of FIG. 1, the selected polymeric materials areextruded simultaneously, presenting a selected tie-layer initiallycontacting a single activated-surface presented at a surface temperaturecorrelated with the selected polymeric material. That tie-layer and acompatible polymeric material for the externally-located finish-layerare co-extruded widthwise of the elongated substrate so as to extend toits lateral edges; and, extruded further establishing dual-layerpolymeric material overhang, beyond each lateral edge of a singlein-line activated-surface.

[0017] The molten polymeric materials, as co-extruded presentingdual-function layers, are solidified at Station 16. That solidificationis initiated in-line by the tie-layer contacting the singleactivated-surface of the rigid sheet metal; the latter is at atemperature significantly less than the extrusion temperature for themolten film; and, less than the melt temperature for the polymericmaterials. Additionally, in-line contact of the polymeric externalfinish-layer with a controlled in-line temperature-modulating surfaceaugments heat removal for such solidification; such added heat removalmeans are disclosed in more detail in relation to later apparatuspresentations.

[0018] In-line heat-removal is selected at Station 16 to achieve desiredsolidification of the polymeric materials at the selected in-lineproduction travel rate; taking into consideration correlated temperatureof the substrate surface based on selection of the tie-layer polymericformulation.

[0019] Trimming solidified lateral-edge polymeric-overhang at eachlateral edge is also carried out at Station 16. Extruding and trimmingpolymeric overhang contribute to uniform polymeric thickness acrossstrip width. Polymeric coating thickness can also be measured at Station16, so as to enable feedback data for maintaining substantially-uniformdesired coating thickness on the single activated-surface during in-lineoperations.

[0020] The remaining opposed corrosion-protected surface of thesubstrate is then activated while traveling in-line at Station 17 ofFIG. 1. Surface-activation is carried-out, as described in relation tothe first activated-surface, by selecting from the group consisting ofopen flame treatment, corona-discharge treatment, and a combinationthereof. The number of open-flame burners and/or corona-discharge units,extending across strip width, is selected based on line speed andsurface conditions. The oxidizing action on the surface causes loss ofsurface electrons which facilitates a chemical bonding of the polymerictie-layer, which is organic with the inorganic metallic protectivesurface during in-line travel.

[0021] Thermoplastic polymeric materials, formulated as described, aresupplied, then heated above melt temperature and pressurized, ascombined, presenting a tie-layer and externally-located finish later atStation 18 of FIG. 1. The tie-layer polymeric formulations are utilizedwith a correlated-temperature for the activated-surface enabling desiredmolten film surface coverage. For example, the ethylene-modifiedpolyethylene terephthalate (PET) utilizes heating of theactivated-surface to a temperature in the range of about 230° to about300° F.; whereas, an anhydride-modified polyethylene utilizes an ambienttemperature surface, free of any heating requirement, for desiredcoverage of the activated-surface. The selected tie-layer providesgreen-strength adhesion with the metallic-surface for in-line travel ofthe dual-layers with the substrate.

[0022] The selected polymeric materials for the dual-function layers areco-extruded under pressure at Station 19. The selected polymericformulation for the tie-layer contacts the activated metallic surfacefor adhesion with that surface; while also providing interlinkage withthe selected polymeric material for the externally-located finish-layer;the latter is in overlapping and co-extensive relationship with theinner-located tie-layer. At Station 19, those combined polymericmaterials are extruded simultaneously widthwise of the remainingactivated surface; while also extending co-extrusion to produce apolymeric overhang at each lateral edge of the moving substrate.

[0023] Solidification of the molten thin-film is initiated by contact atthe tie-layer with the activated inorganic metallic surface at Station20; and, heat removal is augmented by contact of the finish-layerpolymeric material with an in-line surface at a controlled-temperature.That in-line travel and temperature control are described in more detailin relation to later description of apparatus of the invention.Following solidification of the extruded layers, polymeric overhang ateach lateral edge is trimmed at Station 20.

[0024] Extruding a polymeric overhang, solidifying and trimming removalof that overhang contribute the capability for obtaining a uniformpolymeric coating thickness across on each surface. That is, a tendencyfor “necking-in” of polymeric materials had been found to exist near theterminating ends of an elongated molten film extrusion. That potentialedge build-up problem has been eliminated by depositing an overhang ofpolymeric materials beyond each lateral edge of the substrate; and,after solidification, trimming that overhang. The resulting coatingthickness across substrate width can then be substantially uniform; thatenables coating thickness measurements at Station 20 which can be usedto provide feedback data for maintaining desireduniform-coating-thickness extrusion on that surface during in-lineoperations.

[0025] Finishing processing steps for the dual-layer polymericmaterials, on each surface, are initiated at Station 21. The solidifiedpolymeric materials on both surfaces are heated so as to establish melttemperature characteristics substantially-simultaneously. High-frequencyinduction heating helps to rapidly increase the temperature of bothexterior metallic surfaces of the substrate. Heating of those surfaces,in turn, can promptly establish melt-temperature for the polymericmaterials on each metallic surface during in-line travel. A combinationof induction heating of the metal substrate, with penetrating infra-redheating externally-applied to the polymeric materials can be used tocontribute to achieving uniformity of heating throughout the polymericlayers; and, also, for example, can enable decreasing induction heatingfor a composite-coated tin-plated flat-rolled steel product; thusavoiding induction-heating such a surface to a temperature which meltsthe tin plating. The combination of high-frequency induction heating andinfra-red heating can also be helpful for establishing melt-temperaturecharacteristics, for polymeric materials on both surfaces at productionline speeds, which can extend above about five hundred feet per minuteto about eight hundred feet per minute.

[0026] Selected travel of the polymeric coated substrate, atfinishing-process temperature, is carried out at Station 21 prior toinitiating coating. That in-line travel interval facilitates fullcoverage bonding of the tie layer with the topography of the metalliccoating, on each opposed surface; and, also contributes to interlinkingof both dual-layer polymeric materials on each respective activatedmetallic surface.

[0027] After holding the dual-function polymeric materials at finishingtemperature, on both substrate surfaces, for selected in-line travel asindicated at Station 21, the polymeric materials on each surface arerapidly cooled through glass transition temperature at station 22 ofFIG. 1. Rapid cooling through glass-transition temperature providesamorphous characteristics throughout the polymeric coating materials.Amorphous polymeric coating characteristics contribute to desiredfabricating functions for the composite-coated product; especially inindustries which involve fabricating of composite-coated selectedflat-rolled sheet metal for containers, appliances, transportationequipment, and building structures. After rapid cooling, the compositecoated work product is prepared for shipping, by coiling or preparingpacks of cut sheets, at station 22 of FIG. 1.

[0028] Surface-activation apparatus, of FIG. 2, as shown in across-sectional vertical plane which is oriented perpendicularly to thesubstantially-planar elongated flat-rolled metal substrate surface, andextends in parallel relationship to the longitudinal direction ofsubstrate travel. Rows of open-flame impingement burners, extendwidthwise of the substrate, within flame-impingement chamber 24. Thenumber of burner rows is selected dependent on line speed and conditionof the strip surface. A single-surface at a time is activated forpolymeric coating of that surface. That arrangement facilitatescontinuous-line operations; and, also, enables selecting differingpolymeric materials for each opposed surface in continuous-lineoperations. The open-flame treatment burns-off light surface oilsincluding associated debris, if any; and, activates the surface forenhancing polymeric adhesion.

[0029] The content and action of the flame impingement can implementchemical bonding of the organic polymeric tie-layer material with theinorganic metallic surface. The inorganic-metallic protective coating isselected and carried out to enable surface activation for desiredpolymeric adhesion for the composite-coated work product. Such inorganicprotective processing for the selected flat-rolled sheet metals isdescribed, with tabulated data, in relation to later expandedcross-sectional views of composite-coated work product.

[0030] In chamber 25 of FIG. 2, a selected number of rows ofcorona-discharge electrodes extend widthwise of the substrate. Coronadischarge takes place across full-surface width for establishing, and/ormaintaining, activation of the single surface for polymeric coating.Corona discharge ionizes gas contiguous to the metallic substratesurface, safely, by selecting electrical energy level per square foot ofsurface area. The gas ionizing means and energy level are selected basedon strip width and the line-speed selected for continuous-lineoperations. Continuous-line operations provide for polymeric coating ofboth surfaces, one-at-a-time, in a single line; and, a separatepre-treatment apparatus is provided in-line for each surface.

[0031]FIG. 3 shows an enlarged view of extrusion and associatedapparatus provided for each surface, in continuous line operations. Thatapparatus receives, prepares and extrudes polymeric materials. Thepolymeric materials, as selected, for each layer, are suppliedseparately as solid pellets to hoppers 26 and 27, respectively of FIG.3. Thermoplastic polymeric materials as formulated are selected to becompatible and capable of combined molten film extrusion so as topresent an inner- located layer of polymeric material for bonding with ametallic activated-surface; and, with an externally-located finish-layerpolymeric material. The inner-located polymeric material adheres to theactivated-surface so as to provide green strength adhesion for in-linetravel of both layers. The polymeric materials are also selected toprovide polymeric surface properties which, complement the metalcomponent properties of the composite-coated product, and augmentperformance and durability of market-usage products.

[0032] The thermoplastic polymeric materials are separately supplied andmelted, then, heated and pressurized in preparation for and duringcombination for extrusion. In FIG. 3, the polymeric formulation for theinner-located tie-layer portion is directed from hopper 26; and, thepolymeric material for the external-finish layer portion is directedfrom hopper 27; each polymeric material is fed into its respectivemelting and pressurizing means of feed section 28. Each thermoplasticpolymeric material continues to be heated and pressurized duringmovement through a combined-polymer feed chamber 29; which leads toextrusion die 30, for simultaneous thin-film extrusion as combinedpolymeric materials; each layer is distinctly located for functioning,on each opposed surface, of the extruded film.

[0033] In FIG. 3, the activated-surface of substrate 31 travels in-linecontiguous to a penetrative radiation heating source, such as infra-redsurface heater 32; which can be energized by switch means as shown. Theuse of surface heater 32 is dependent on the formulation selected forthe tie-layer of the dual-layer polymeric materials. For example,ethylene-modified polypropylene terephthalate (PET), utilizes acorrelated activated-surface temperature of about 230° F. to about 300°F. in order to obtain desired coverage of the activated-surface. Amaleic-anhydride polyethylene tie-layer formulation has been found toprovide desired characteristics for bonding with an activated metallicsurface at ambient temperature; that is, use of a surface heater 32 isnot required. Characteristics for an inner-located tie-layer are alsodescribed in more detail in relation to expanded cross-sectional viewsof work product produced in accordance with the invention.

[0034] The combined molten polymeric materials continue to be heated andpressurized in extrusion die 30; which presents oriented to extendwidthwise of the elongated substrate. The thermoplastic materials areheated significantly above melt temperature for extrusion through thatopening of die 30, as an elongated narrow-opening nozzle aswidthwise-oriented in relation to the activated surface.

[0035] Referring to FIG. 3A, which is an expanded view of a portion ofFIG. 3, substrate 31 is directed toward a coating nip, which is definedbetween pressure-roll 33 and temperature-modulating roll 34. Die 30extends toward and extrudes the combined polymeric materials molten-filminto that coating nip. The inner-located molten tie-layer of theextrusion contacts the activated-surface of substrate 31; and, thepolymeric material for the externally-located finish-layer, which is inoverlapping, co-extensive relationship with the tie-layer, is extrudedinto that coating nip so as to contact the peripheral surface oftemperature-modulating roll 34 of FIG. 3A.

[0036] Each layer is quantitatively selected and the combined polymericmaterials are heated to a temperature selected between about 475° F. toabout 550° F. for providing for desired molten thin-film extrusion. Theinner-located polymeric tie-layer, as extruded from die 30, issubstantially thinner than the polymeric externally-locatedfinish-layer. Polymeric solidification is initiated by contact with theactivated-surface of rigid flat-rolled sheet metal substrate 31, whichis free of a heating requirement, presenting an ambient temperature ofabout seventy to about ninety-five degrees Fahrenheit. Roll 32 exertsnominal pressure against substrate 31; urging contact of theactivated-surface with the thin tie-layer portion of the extrusion andbetween the dual-layers 34 and 35 while also urging contact offinish-layer 35 with the in-line traveling peripheral surface oftemperature-modulating roll 33.

[0037] The peripheral surface of temperature-modulating roll 33 istemperature-controlled. That peripheral surface is preferably coatedwith a thin ceramic, covering a highly heat-conductive metal roll suchas nickel-chromium steel. One method for adequately cooling theperipheral surface of temperature-modulating roll 34 is circulatingcoolant internally of the roll; the peripheral-surface temperature forroll 33 is maintained substantially in the range of about fifty to aboutseventy-five degrees Fahrenheit (50° F. to about 75° F.) when using atie-layer requiring heating of the activated surface to a temperature inthe range of 230° F. to 300° F.

[0038] That temperature implements solidification of the entirethickness of the combined molten extrusion during travel in-line on aselected portion of the peripheral-surface, as indicated, thattemperature also facilitates separation of the coated substrate from thethin ceramic surface of Roll 34 for in-line travel, while enablingdesired conductive heat transfer for solidifying the polymericcombination during contact with roll 34.

[0039] In continuous-line apparatus, as shown in the general-arrangementview of FIG. 4, each opposed substrate surface is activated separately,followed by extrusion of the combined polymeric materials forassociation with that single activated-surface. Continuous-strip 36,formed by welding together leading and trailing ends of coiled sheetmetal substrate, in coil ramp 38, is fed through looping pit 39; thelatter enables operation of the coil-ramp apparatus for welding togethercontinuous-strip for in-line operations; free of interruptions whilechanging-coils for feeding sheet metal into the line.

[0040] Pre-treatment apparatus 40, described in detail in relation toFIG. 2, includes two rows of open-flame burners and corona-dischargeelectrodes acting across the surface being activated. The metalliccorrosion-protection coating for opposed surfaces of the selectedflat-rolled sheet metal is selected so as to be capable of activation,by activation means as selected.

[0041] Dependent on the selected polymeric material for the innertie-layer portion of single-surface activated strip 41, an infra-redheater 42, operated in cooperation with switch 43, enables surfaceheater 42 to be turned on, if required. Ethylene-glycol modified PET,for example, utilizes a correlated-temperature for the activated-surfaceof about 230° F. to about 300° F., as heated by heater 42. Athermoplastic polymeric formulation of maleic-anhydride modifiedpolyethylene enables utilizing an ambient-temperature activated-surface;that is free of a surface heating requirement.

[0042] Formulated thermoplastic polymeric materials are supplied assolid pellets separately for each layer; hopper 44 receives theinner-located tie-layer polymeric material; and, hopper 45 receives forthe externally-located finish-layer polymeric material of the combinedextrusion. The polymeric materials are melted in heating apparatus 46.Heating and pressurizing of the combined polymeric materials thencontinues in feed chamber 47 leading to narrow-opening die 48 forextrusion at a temperature, selected in a range of about 450° F. toabout 550° F. for thin-film extrusion.

[0043] A polymeric coating nip (as better seen in FIG. 3A) is definedbetween roll 49 and temperature-modulating roll 50; while rotating asindicated by the direction of strip travel in FIG. 4. Strip 41 travelstoward roll 49 and into that defined coating nip, presenting itsactivated-surface for contact with the thin tie-layer of the combinedextrusion from die 48. The tie-layer polymeric material is selected tohave sufficient green-strength adhesion to provide for combined travelof the dual-layers with the activated-surface of strip 41.

[0044] The selected polymeric formulation for the externally-locatedfinish-layer, of the extruded film is in overlaying and co-extensiverelationship with the inner-located tie layer, of the combinedextrusion, during travel of substrate 41 into the defined coating nip.Nominal pressure is exerted by roll 49 on that combination of strip andpolymeric materials while in the defined nip. The polymeric materialsare extruded from the narrow-opening of die 48 to extend across stripwidth; and, further, to extend beyond each lateral edge of the strip,forming a polymeric overhang.

[0045] The activated-surface of the strip is at a temperaturesubstantially less than extrusion temperature, and less than melttemperature for the thermoplastic polymeric materials, such thatpolymeric solidification is initiated by contact of the inner-tieportion with the activated-surface. In addition, the peripheral surfaceof temperature-modulating roll 50 is maintained within a selected range,by circulating coolant internally, so as to solidify the polymericlayers during contact of the externally-located polymeric finish layerwith an in-line peripheral-surface portion of roll 50; the solidifiedsingle-surface polymeric coated product then separates from roll 50 forin-line travel toward roll 51.

[0046] Solidified polymeric overhang is removed at trimmer means 52;and, the polymeric coating thickness is measured by thickness gauge 53.The thickness gauge data can provide feed-back data automaticallycontrolling the extrusion means; or, can be communicated directly foruse by the line operator so as to help maintain uniform polymericcoating thickness, on the single-coated surface, during in-lineoperations.

[0047] Single-surface polymeric-coated strip 54, traveling as indicated,presents its remaining non-polymer-coated surface for activation inpre-treatment apparatus 55. Rows of open-flame burners burn-off lightsurface oil and associated debris, if any, as well as activate thesurface for enhanced polymeric adhesion. Also, rows of corona-dischargeelectrodes extend across strip width, so as to implement, or augment,that surface activation.

[0048] Strip 56, presenting such activated-surface, is directed fortravel contiguous to surface-heater 57. When required, dependent onselection of the polymeric formulation for inner tie-layer of thecombined extrusion film, infra-red surface heater 57 can be energized bymeans of power-source switch 58. Strip 56 is then directed toward acoating nip (as better seen in FIG. 3A) defined between roll 59 andtemperature-modulating roll 60.

[0049] Selected formulated thermoplastic polymeric materials areseparately supplied; as solid pellets for the inner-located thin-filmtie-layer portion of the combined extrusion, and as solid pellets forthe overlapping and co-extensive finish-layer to hoppers 61 and 62,respectively. Each polymeric material is melted at heating apparatus 63;heating and pressurizing continue in chamber means 64 leading toextrusion die 65 which presents an elongated narrow-opening orientedwidthwise of strip 56.

[0050] Strip 56 contacts pressure-roll 59, for entry into the coatingnip defined between roll 59 and temperature-modulating roll 60. Thepolymeric material for the inner-located tie layer of the extrusioncontacts the activated- surface of strip 56; and, the externally-locatedfinish-layer polymeric material contacts temperature-modulating roll 60.Nominal pressure is exerted by pressure-roll 59 urging their combinationduring travel through the defined coating nip.

[0051] The peripheral-surface of temperature-modulating roll 60 ismaintained at a selected temperature; as determined by the tie-layerformulation,, by circulating such coolant internally for completingsolidification of the selected dual-layer polymeric materials fordeparture from roll 60 toward roll 66. Solidified polymeric overhang,extending beyond each lateral edge of the strip is removed by trimmingmeans 68; and polymeric-coating thickness on such surface, is measuredat thickness gauge 70; the latter can use infra-red or other penetrativeelectromagnetic energy. Feedback of polymeric thickness can be directedeither electronically to the polymeric feed means, or to a line operatorfor control, so as to maintain uniform polymeric coating on thatsingle-surface coating during in-line operations.

[0052] Continuous-strip 72, with polymeric coatings on each surface, isdirected for finishing-processing which are initiated by remelting thepolymeric materials on each surface in heating means 73. High-frequencyinduction heating concentrates heating at each surface of the metalstrip, and facilitates remelting at line speeds from 500 to 800 fpm.Heating means 73 can also include infra-red heating means forpenetrative heating from the direction of each external surface, forsubstantially uniform heating and remelting of the polymeric materialson each surface. Strip travel, with remelted dual polymeric materials oneach surface, continues in-line as indicated, to permit augmentedbonding with the metallic-protective coating and between the dual-layerpolymeric materials on each opposed surface.

[0053] The remelted polymeric layers are then rapidly-cooled, throughglass-transition temperature utilizing quench bath 74, and associatedmeans, so as to produce amorphous characteristics throughout thepolymeric materials on each surface. Cooling of quench solution, whichcan be de-ionized water or tap water, can be augmented by pumping of thecooling solution through line 75 to re-entry portion 76, which directsthe cooling solution so as to provide laminar flow on each surfaceduring strip travel. Also, a closed heat-exchanger system 77 can beutilized to remove heat from the bath solution, as needed, dependent online speed.

[0054] Wiper rolls 78 return cooling solution from the exiting polymericcoated strip 79 to bath 74; and, blower 80 dries the surfaces of strip79. Looping tower 81 and bridle-roll station 82 provide for handling ofcontinuous-strip 79 in preparation for shipment. Corona discharge of thepolymeric coating can, optionally, be carried-out on one or bothpolymeric coated surfaces at unit 83 for purposes of augmenting printingon a selected market-usage product. Or, the dual polymeric-materialcoated strip 79 can be directed, by means of travel path 84, to station85, where the composite-coated material is prepared for shipment; suchas: by coiling or being cut and formed into coated-sheet stacks.

[0055] Flat-rolled sheet metal, corrosion-protective metallic coating,and the dual thermoplastic polymeric materials are each selected andcombined to supply composite-coated work product to selected industriesfor fabricating surface-finished products, or portions ofsurface-finished products, for assembly.

[0056] Corrosion-protection is selected, for rigid flat-rolled sheetmetal, which is capable of being activated for polymeric adhesionpre-treatment. Both sheet-metal surfaces are corrosion-protected; andeach surface is coated with dual-function polymeric materials, asdescribed in relation to FIGS. 1-4. The flat-rolled sheet metal isselected with a thickness gauge greater than foil-gauge, for theselected sheet metal. As shown in FIGS. 5-7, each surface of the rigidsheet metal includes a metallic corrosion-protection coating, as well asdual-functioning polymeric materials.

[0057] Referring to the expanded cross-sectional view of FIG. 5, rigidflat-rolled low-carbon steel 85 having a carbon content of about 0.2% toabout 3.5% includes single-reduced flat-rolled steel with a tensilestrength of about 40,000 to 60,000 psi; or, double-reduced, without anintermediate anneal, flat-rolled steel having a tensile strength ofabout 80,000 to 100,000 psi. Surface oxidation is removed by acidpickling, or caustic-solution cleansing steps, before coating aninorganic-metallic protective coating. Coated flat-rolled steel coils,as disclosed herein, can be wrapped for shipment as shown in co-ownedU.S. Pat. No. 5,941,050, issued Aug. 24, 1999, which is included hereinby reference.

[0058] Thickness gauges for flat-rolled steel 85 of FIG. 5 metalliccorrosion-protection 86, 87 for each respective steel surface areselected from the following table: TABLE I Steel ThicknessInorganic-Metallic Coating about .004″ electrolytic plated tin about.025 to to about measured in pounds per base about 1.35 lb/bb .015″ box,which equals 33,360 sq. in. same TFS (tin-free steel); about 3 to 13mg/ft² electrolytic plated chrome and chrome oxide about .7 to 2.5mg/ft² same cathodic dichromate dip- about 50 mg/ft² coating throughelectrolytic to about 600 mg/ft² coating same electrolytic plated zincabout .025 oz/ft² to about .175 oz/ft² about .01″ to hot-dipped zincspelter .0005″ to about about .035″ (thickness each surface) .0015″

[0059] A hot-dip zinc spelter galvanizing bath includes molten aluminumin a range from minor percentage by weight of less than two percent tohigh aluminum percentage Galvalume™. Hot dip galvanizing weights can beapplied from about twenty-five to about one hundred fifty oz/ft², totalboth surfaces. A differential zinc-spelter coating weight can beprovided on each surface dependent on market-usage; also, a light-weightzinc-spelter coating can be alloyed with the flat-rolled steel surface.Dual-function combined thermoplastic polymeric-materials coated on eachsurface of hot-dipped zinc-spelter protected flat-rolled steel provideslong-term durability for market-usage in appliances, automotive andother transport vehicle industries, and the construction industry.

[0060] In FIG. 5, each corrosion-protected surface is coated withcombined dual-function thermoplastic polymeric materials 88, 89;selected for inner tie-layer and exterior finish-layer portions asidentified and described in the following tabulation: TABLE IITemperature Location of Activated-Surface Polymeric Layer PolymericMaterial for Coating inner-located tie- (i) ethylene-glycol 230°-300° F.layer modified PET (ii) maleic anhydride- ambient. modified polyethyleneexterior-located (i) combination PBT and can be coated at finish-layerPET ambient temperature, (ii) PBT, or and can be (iii) PET coated attemperature of the inner- located tie-layer

[0061] The polymeric material selected for the inner tie-layer, and forthe exterior finish-layer can differ on each surface. That selection canbe at least in part based on market-usage, and exposure conditionsduring market-usage. Total combined polymeric coating thickness on eachsurface is preferably at least about one mil (0.001″) in thickness ofwhich about fifteen to about thirty-three and-a-third percent is theinner tie-layer; and, about sixty-six and two-thirds percent to abouteighty-five percent is the externally-located finish-layer. Quantitativepolymeric extrusion can be controlled on each metallic surface.

[0062] In FIG. 6, flat-rolled aluminum 90 can be selected in a thicknessrange of about 0.005″ to about 0.25″; aluminum oxide provides aninorganic-metallic protective coating, which can be activated forpolymeric adhesion. Other protective coatings 91, 92, are provided byselecting either chromizing, or chemical or electrochemical conversioncoating or chromate coating. Protective coating 91, 92 can have alighter-weight aluminum oxide coating, or a selected weight in a rangeabout fifty to about six hundred micrograms per square foot for theother named protective coatings.

[0063] The dual-function polymeric materials indicated at 93, 94 of FIG.6 are selected as identified in Table II and described earlier. Thecomposite-coated flat-rolled aluminum sheet metal work product of FIG. 6contributes formability, durability, and light weight where preferredfor market-usage utility in the container industry, or for usage inconstruction calling for light-weight products for on-site fabrication,such as rain-gutters, and the like.

[0064] The aluminum/magnesium alloy 95 of FIG. 7 can be selected in athickness range of about 0.0045″ to about 0.2″ with protective coating96, 97 in the form of a lighter-weight oxide or selected as describedfor aluminum in FIG. 6; the latter having a weight in a range of aboutfifty to about six hundred micrograms per square foot. The combinedextrusion dual-function polymeric materials 98, 99, for eachcorrosion-protected surface, are selected from those identified in TABLEII.

[0065] The relatively high tensile strength and impact resistence of thecomposite coated aluminum/magnesium alloy sheet metal of FIG. 7increases utility and contributes performance for market usage productswhere high-strength and light-weight both play important roles, forexample, in the fields of construction products used duringconstruction, such as scaffolding, etc., and in the automotive and othertransportation industries.

[0066] The described polymeric materials are available from:

[0067] 1. E.I. du Pont de Nemours and Company Barley Mill PlazaWilmington, Del. 19880-0026

[0068] 2. Eastman Chemical Company 100 North Eastman Road P.O. Box 511Kingsport, Tenn. 37662-5075

[0069] 3. ATOFINA Chemicals, Inc. 2000 Market Street Philadelphia, Pa.,19103-3222

[0070] 4. Basell USA 2801 Centerville Road Wilmington, Del.

[0071] 5. Bayer Corporation 100 Bayer Road Pittsburgh, Pa. 15205-9744

[0072] Open-flame burners, to size specifications for the line, areordered from:

[0073] Flynn Burner Corporation 425 Fifth Avenue (P.O. Box 431) NewRochelle, N.Y. 10802

[0074] Corona discharge electrodes are ordered to specification from:

[0075] Enercon Industries Corp. W140 N9572 Fountain Boulevard MenomoneeFalls, Wis. 53052

[0076] The polymeric extrusion apparatus, for the polymeric layersdescribed above, can be ordered to specifications, consideringline-speed, from:

[0077] Black Clawson Converting Machinery, LLC 46 North First StreetFulton, N.Y. 13069

[0078] Specific values, dimensional relationships, combinations ofmaterials, method steps, products and apparatus have been set forth forpurposes of disclosing embodiments of the invention; however, it shouldbe recognized that, in the light of those disclosures, others have beentaught principles which enable making minor changes in those specifics,while continuing to rely on the teachings and principles of theaccompanying disclosure. Therefore, for purposes of determining thepatentable scope of the disclosed subject matter, reference should bemade to the appended claims.

1. Composite-coating of elongated flat-rolled sheet metal substrate, comprising A) supplying elongated flat-rolled rigid sheet-metal substrate by selecting an inorganic-metallic protective coating for each of its pair of substantially-planar opposed surfaces which extend width-wise between longitudinally-extending lateral edges of said substrate, B) controlling substrate movement in the direction of its length; while activating a single inorganic-metallic protected surface of said substrate for enhancing adhesion of extruded molten thermoplastic polymeric material, with such surface-activation being selected from the group consisting of: (i) impinging an open-flame on said single surface for burning-off light oil and surface debris, if any, while controlling chemical content of said flame for producing an oxidizing reaction on such surface causing loss of surface electrons, (ii) ionizing gas contiguous to said surface by corona-discharge for activating said surface, and (iii) combinations of (i) and (ii), in any order; C) presenting said single activated surface for deposition of an extruded molten film of polymeric materials, including: (i) a molten thermoplastic polymeric material tie-layer for first-contacting said activated surface, selected from the group consisting of (a) ethylene glycol modified polyethylene terephthalate (PET) while said activated surface is pre-heated to a temperature of about 230° F. to about 300° F. for to said contact by said tie layer, and (b) anhydride-modified polyethylene while presenting said activated-surface at ambient temperature; and, further including: (ii) a molten thermoplastic polymeric material finish-layer, in overlaying and co-extensive relationship with said tie-layer, selected from the group consisting of (d) a combination of polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), (e) PBT, and (f) PET; D) preparing said selected polymeric coating materials as separately supplied for each said layer, by (i) heating said polymeric materials to melt temperature, (ii) pressurizing and continuing heating said molten polymeric materials, while (iii) combining said polymeric materials for simultaneous molten film extrusion; E) controlling travel of said substrate in the direction of its length presenting said single activated surface, while selectively including pre-heating said surface for coverage when said combined tie-layer polymeric material consists essentially of said ethylene glycol modified PET; F) extruding said molten-film polymeric materials under pressure, with (i) said tie-layer being inner-located for first-contacting said activated surface, and with (ii) said finish-layer being externally located in overlapping and co-extensive relationship with said tie-layer; G) depositing said molten film polymeric materials simultaneously to extend widthwise between lateral edges of said strip, and to extend further (i) forming a polymeric-overhang of said dual layers extending beyond each lateral-edge of said activated-substrate surface, followed by (ii) removing heat from said polymeric materials (a) by initial contact of said tie-layer with said substrate surface, (b) by contact of said finish-layer with an in-line temperature-modulating surface, including (c) controlling temperature of said in-line surface, for completing solidification of said polymeric materials; then H) activating the remaining opposed substantially-planar surface of said elongated substrate while traveling in the direction of its length, by carrying-out said steps, as set forth in Paragraph B above, for enhancing adhesion of polymeric materials on said remaining activated surface; I) presenting said activated surface for molten-film extrusion of thermoplastic polymeric materials, as set forth in Paragraph C) above; including J) preparing said polymeric materials for extrusion as set forth in Paragraph D) above; K) controlling travel of said substrate in the direction of its length, as set forth in Paragraph E above; L) presenting said remaining activated-surface for molten-film extrusion coating by said molten polymeric materials, under pressure, as set forth in Paragraph F) above; M) depositing said combined molten polymeric materials with respect to said remaining activated-surface and solidifying said layers as set forth in Paragraph G) above; followed by N) remelting said dual-layer polymeric materials simultaneously on each said surface of said elongated substrate while said substrate is traveling in the direction of its length; including the steps of: (i) selecting a remelt temperature for both said polymeric layers on each surface, (ii) providing for in-line travel of such substrate in the direction of its length substantially at said remelt temperature, prior to initiating cooling, so as to enable completing coverage by said first-contacting tie-layer with said inorganic-metallic topography on each substrate surface; and, also for (iii) augmenting interlinking of polymeric materials of said tie-layer and said external-finish layer, on each said opposed substrate surface; then O) rapidly cooling said dual-layer polymeric materials substantially-simultaneously on both said opposed surfaces through glass transition temperature, resulting in (i) establishing amorphous characteristics in said polymeric coating materials on each said opposed surface, while also (ii) cooling said metal substrate to a temperature to avoid later raising said polymeric materials to a glass transition temperature; and Q) directing said elongated substrate, as composite coated on both surfaces, for assembly in a form suitable for transfer.
 2. The process of claim 1, further including subsequent to solidification of said polymeric materials as associated with each respective surface, trimming said polymeric overhang as associated with each said surface, and measuring thickness of said dual-layer polymeric materials on each respective surface for maintaining desired uniform coating on each said respective surface.
 3. The process of claim 2, comprising: selecting flat-rolled rigid sheet metal substrate from the group consisting of (i) low-carbon steel, (ii) aluminum, and (iii) aluminum/magnesium alloy.
 4. The process of claim 3, including (a) selecting rigid flat-rolled low-carbon steel substrate having a thickness gauge in a range about 0.004″ to about 0.015″, and (b) selecting an inorganic non-ferrous metallic protective coating, for each said opposed substantially-planar surface of said steel substrate, from the group consisting of: electrolytic plated tin electrolytic-plated chrome/chrome oxide electrolytic-plated zinc cathodic-dichromate, and hot-dip coated zinc spelter.
 5. The process of claim 3, including (a) selecting rigid flat-rolled substrate, from the group consisting of (i) aluminum having a thickness gauge of about 0.005″ to about 0.15″ (ii) aluminum magnesium alloy having a thickness gauge of about 0.0045″ and above 0.15″, with (b) an inorganic metallic protective coating for each opposed planar surface selected from the group consisting of (1) surface oxidation, (2) a chemical conversion coating, (3) an electrochemical conversion coating (4) chromizing, and (5) a chromate coating.
 6. The process of claim 4, including (a) selecting flat-rolled low-carbon steel substrate having a hot-dip zinc spelter coating, with spelter coating thickness being in the range of about 0.0005″ to a bout 0.0015″ total both surfaces, and, further (b) selecting, for inclusion in said thermoplastic-polymeric material finish-layer, for at least one substrate surface, an antimicrobial agent selected from the group consisting of: (i) particulate copper, and (ii) particulate silver encased in zeolite.
 7. Engineered-composite-coated material, comprising (a) rigid flat-rolled sheet metal substrate, having opposed substantially planar surfaces, and (b) solidified polymeric-coating materials, produced with polymeric overhang at each lateral edge, which is trimmed for measuring polymeric coating thickness on each said planar surface of said substrate, in accordance with the process of claim
 3. 8. Engineered-composite-coated material, comprising (a) rigid flat-rolled low-carbon steel substrate, having opposed substantially planar surfaces, with (b) non-ferrous inorganic-metallic protective coating on each surface, produced in accordance with the process of claim
 4. 9. Engineered-composite-coated-material, comprising (a) rigid flat-rolled sheet metal substrate with inorganic metallic protective coating on each opposed planar surface, produced in accordance with the process of claim
 5. 10. Engineered-composite-coated material, comprising (a) hot-dip zinc spelter coated elongated rigid flat-rolled low-carbon steel substrate; presenting (b) solidified polymeric material as an externally-located finish-layer on each such surface; in which, at least one said externally-coated finish-layer, includes (c) an antimicrobial agent established in accordance with process of claim
 6. 11. In-line apparatus for molten polymeric film extrusion-coating of elongated flat-rolled sheet metal, comprising: A) means supplying elongated flat-rolled rigid sheet-metal substrate, traveling in-line in the direction of its length, with both substantially-planar opposed presenting an inorganic-metallic protective surface extending width-wise between longitudinally-extending lateral edges of said strip; B) in-line means for activating a single such substrate surface at-a-time in preparation for molten film polymeric extrusion coating of such single activated surface, in which (i) said surface-activation means are selected from the group consisting of: (a) means impinging controlled-content open-flame on said single surface for burn-off of light surface oil and associated surface debris, if any, while producing an oxidizing reaction causing loss of surface electrons, for enhanced polymeric adhesion, (b) corona-discharge means for ionizing gas contiguous to said single surface, free of electric arcing, for activating said surface for enhanced polymeric adhesion, and (c) combinations of (a) and (b), in any order; C) means for presenting such substrate for adherence of molten-film extruded thermoplastic polymeric materials to said single activated surface for travel with said elongated substrate, including: (i) means for supplying a pair of distinct thermoplastic polymeric formulations capable of compatible combined simultaneous molten film extrusion, so as to present a thermoplastic inner-located tie-layer and an externally-located thermoplastic finish layer; with (ii) said tie-layer in said simultaneous extrusion being selected from the group consisting of: (a) ethylene glycol modified polyethylene terephthalate (PET), by utilizing in-line pre-heating means to establish said activated-surface at a temperature in the range of about 230° F. to about 300° F., for desired surface coverage by said tie-layer polymeric material, and (b) anhydride-modified polyethylene, with said activated surface being presented at ambient temperature; with D) said finish-layer thermoplastic polymeric material being selected from the group consisting of: (i) a combination of polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), (ii) PBT, and (iii) PET; E) polymeric material handling means for receiving said polymeric materials, melting said selected tie-layer and finish-layer thermoplastic polymeric materials, and combined heating and pressurizing of said tie-layer and finish-layer polymeric materials for simultaneous molten-film extrusion; F) extrusion means for said combined polymeric materials, including (i) die means presenting a extended-length narrow nozzle opening for molten-film extrusion of said combined molten pressurized polymeric materials, with said nozzle-opening being oriented, so as (ii) to extend widthwise of said substrate to each lateral edge of such substrate, and to extend further so as to (iii) establish polymeric overhang, of said combined polymeric materials, beyond each said lateral edge of said surface, in which (iv) said tie-layer of said combined extruded-film polymeric materials is located so as to initially contact said activated-surface, and (v) said finish-layer is located, externally, of said combined polymeric materials, coextensive with said tie-layer; G) in-line heat removal means for said combined polymeric materials, including (i) initial contact of said tie-layer with said activated surface; (ii) in-line rotatable roll means presenting a peripheral-surface for contact by said externally-located finish-layer of said extruded polymeric materials, during in-line travel of said substrate in the direction of its length, and (iii) means for cooling said peripheral-surface of said roll means for completing solidification of said combined polymeric materials by said in-line contact of said peripheral surface; H) (i) in-line edge trimmer means for removing solidified polymeric overhang along each lateral edge, while said elongated substrate is traveling in the direction of its length, and, (ii) subsequently located in-line means for measuring polymeric thickness on said single-activated surface, so as to enable maintaining uniform polymeric thickness, during in-line operations; subsequently located I) in-line means for activating solely the remaining opposed substantially-planar surface of said substrate, in which (i) surface pre-treating means are selected from the group as set forth in Paragraph B above, while (ii) said strip is traveling in the direction of its length; J) means presenting said remaining surface as activated for receiving tie-layer polymeric materials, selected as set forth in Paragraph C) above; with K) means for delivering finish-layer polymeric materials selected as set forth in Paragraph D) above; L) polymeric handling means for separately receiving and melting said polymeric materials for said layers, and heating and pressurizing polymeric materials in combination for said layers, as set forth in Paragraph E) above, M) thin-film extrusion means for said combined polymeric materials, including die means with an extended-length nozzle-opening, oriented for molten film extrusion widthwise extending across said substrate activated surface, and, extending further, to establish polymeric overhang along each lateral edge of said substrate, as set forth in Paragraph F) above; N) in-line heat-removal means including rotatable roll means presenting a cooled peripheral surface, as set forth in Paragraph G) above, for solidification of said polymeric materials; O) (i) in-line edge trimmer means for removal at each lateral edge of solidified polymeric overhang, during travel of said substrate in the direction of its length; and (ii) in-line means for measuring polymeric coating thickness on said surface for maintaining uniform polymeric coating thickness during in-line operations; and P) finishing-processing means for polymeric materials on each said substrate surface, including (i) polymer remelting means, including high-frequency induction heating means for surface heating of said substrate, while traveling in the direction of its length, so as to heat said polymeric materials on each said surface of said substrate to establish melt temperature characteristics, and (ii) means providing for travel of said polymeric-coated substrate with said established melt temperature characteristics for said polymeric materials, prior to initiating cooling, so as to: (a) facilitate completing surface coverage, by said tie-layer with said activated-surface topography on each said surface, and (b) augment polymeric interlinking of said coextensive finish-layer with said tie-layer on each said surface; followed by R) cooling means, including quench bath means for rapidly cooling said polymeric materials associated with each said metallic surface through glass transition temperature, for producing substantially-amorphous characteristics in said dual-layer polymeric materials on each surface, and S) means for preparing said dual-surface polymeric-coated substrate for transfer.
 12. The continuous-in-line apparatus of claim 11, including means for supplying inorganic-metallic protective-coated rigid flat-rolled sheet metal substrate, selected from the group consisting of (i) low-carbon steel, (ii) aluminum, and (iii) aluminum/magnesium alloy; in which: (a) said sheet metal supply means delivers flat-rolled low-carbon steel substrate having a thickness gauge in a range of about of about 0.004″ to about 0.015″, including (b) a non-ferrous, inorganic-metallic protective coating, capable of being activated or enhanced polymeric adhesion, on each opposed substantially-planar surface of said steel substrate, selected from the group consisting of: electrolytic tinplate electrolytic-plated chrome/chrome oxide electrolytic-plated zinc cathodic dichromate, and hot-dipped zinc spelter.
 13. The continuous-in-line apparatus process of claim 12, including (i) supply means for flat-rolled low-carbon steel substrate having a hot-dipped zinc spelter coating, and, in which (ii) said external-finish polymeric layer, on at least one of said opposed surfaces, includes an antimicrobial agent selected from the group consisting of (i) particulate copper, and (ii) particulate silver encased in zeolite.
 14. The apparatus of claim 12, including means for supplying flat-rolled sheet metal selected from the group consisting of (i) aluminum having a thickness gauge range of about 0.005″ to about 0.15″, and (ii) aluminum/manganese alloy, having a thickness gauge of about 0.0045″ to about 0.15″, with (iii) each said substrate surface having an inorganic-metallic protective coating, selected from the group consisting of (a) a surface oxide of said selected sheet metal, (b) a chemical conversion coating, (c) an electrochemical conversion coating, (d) a chromizing coating, and (e) a chromate coating. 